linux-kernel - Re: [PATCH net-next 06/15] net: sgi: ioc3-eth: get rid of ioc3_clean_rx

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Date:   Wed, 28 Aug 2019 16:02:46 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Thomas Bogendoerfer <tbogendoerfer@...e.de>
Cc:     Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH net-next 06/15] net: sgi: ioc3-eth: get rid of
 ioc3_clean_rx_ring()

On Wed, 28 Aug 2019 16:03:05 +0200, Thomas Bogendoerfer wrote:
> Clean rx ring is just called once after a new ring is allocated, which
> is per definition clean. So there is not need for this function.
> 
> Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@...e.de>
> ---
>  drivers/net/ethernet/sgi/ioc3-eth.c | 21 ---------------------
>  1 file changed, 21 deletions(-)
> 
> diff --git a/drivers/net/ethernet/sgi/ioc3-eth.c b/drivers/net/ethernet/sgi/ioc3-eth.c
> index 6ca560d4ab79..39631e067b71 100644
> --- a/drivers/net/ethernet/sgi/ioc3-eth.c
> +++ b/drivers/net/ethernet/sgi/ioc3-eth.c
> @@ -761,26 +761,6 @@ static void ioc3_mii_start(struct ioc3_private *ip)
>  	add_timer(&ip->ioc3_timer);
>  }
>  
> -static inline void ioc3_clean_rx_ring(struct ioc3_private *ip)
> -{
> -	struct ioc3_erxbuf *rxb;
> -	struct sk_buff *skb;
> -	int i;
> -
> -	for (i = ip->rx_ci; i & 15; i++) {
> -		ip->rx_skbs[ip->rx_pi] = ip->rx_skbs[ip->rx_ci];
> -		ip->rxr[ip->rx_pi++] = ip->rxr[ip->rx_ci++];
> -	}
> -	ip->rx_pi &= RX_RING_MASK;
> -	ip->rx_ci &= RX_RING_MASK;
> -
> -	for (i = ip->rx_ci; i != ip->rx_pi; i = (i + 1) & RX_RING_MASK) {
> -		skb = ip->rx_skbs[i];
> -		rxb = (struct ioc3_erxbuf *)(skb->data - RX_OFFSET);
> -		rxb->w0 = 0;

There's gotta be some purpose to setting this w0 word to zero no?
ioc3_rx() uses that to see if the descriptor is done, and dutifully
clears it after..

> -	}
> -}
> -
>  static inline void ioc3_clean_tx_ring(struct ioc3_private *ip)
>  {
>  	struct sk_buff *skb;
> @@ -860,7 +840,6 @@ static void ioc3_init_rings(struct net_device *dev)
>  	ioc3_free_rings(ip);
>  	ioc3_alloc_rings(dev);
>  
> -	ioc3_clean_rx_ring(ip);
>  	ioc3_clean_tx_ring(ip);
>  
>  	/* Now the rx ring base, consume & produce registers.  */